Process Encyclopaedia
Friction welding
Overview
Welding is commonly thought of as a process where material is melted - this type of process is more properly called fusion welding. However, there is another type of welding process, called hot welding, where the material is heated until it softens but does not melt. Friction welding falls into the latter category - the heating is provided by the rubbing of the parts to be joined (at speeds which can be up to 15m/s).Materials and shapes
- Usually, at least one of the parts to be joined must be circular - this can be solid or hollow.
- One of the materials to be joined must soften before melting.
- Used to join different materials to each other (e.g. polymers to metals).
- Solid bars up to 100mm can be joined and pipes up to 250mm.
- Good joint quality depends on good alignment of parts and timing of the final forging together.
Economics
- Basic equipment costs around £10,000, but automation can increase this significantly.
- Most suited economically to joining pipes and attaching studs.
- For similar metals, competitive with arc welding for the geometries it can do. But because of the capital cost, it is not competitive where only a small number of joints are required.
- Competitive with adhesives for polymers for the geometries it can do, especially for a large number of joints.
- Removal of flash (if required) adds to the cost.
Typical products